1. Field of the Invention
The present invention relates to a multilayer electronic component which can be contained in an electronic device, and particularly to a multilayer electronic component which constitutes a module for communication with moving objects, a semiconductor package, a hybrid IC, etc.
2. Description of the Related Art
The construction of conventional multilayer electronic components will be described with reference to FIGS. 7, 8 and 9.
Referring to FIG. 7, a multilayer electronic component 51 comprises a substrate 52 and external electrodes 53 which are formed on each of the side surfaces 52a and 52b of the substrate 52. The substrate 52 is formed by stacking a plurality of insulating sheets, including insulating sheets (not shown) provided with internal circuits (not shown), to form a parent laminate (not shown), cutting the parent laminate in accordance with the dimensions of the substrate 52, and then firing the substrate. The external electrodes 53 are formed by applying a conductor to each of the side surfaces in the direction of thickness thereof. In such a multilayer electronic component 51, when a conductor is applied to each of the side surfaces 52a and 52b of the substrate 52, the conductor inevitably adheres to both major surfaces 52c of the substrate 52, thereby forming two ends 53a of each of the external electrodes 53 on the two major surfaces 52c of the substrate 52, respectively.
Referring to FIG. 8, a multilayer electronic component 61 comprises a substrate 62 and external electrodes 64 which are respectively provided in indentations 63 formed in each of the side surfaces 62a and 62b of the substrate 62. The substrate 62 is formed by stacking a plurality of insulating sheets, including insulating sheets (not shown) provided with internal circuits (not shown), and through holes 66, to form a parent laminate 65, applying a conductor to the inner peripheral surface of each of through holes 66 formed in the parent laminate 65, cutting the parent laminate 65 in accordance with the dimensions of the substrate 62, and then firing it. When the parent laminate 65 is cut, the through holes 66 are cut to form the indentations 63, and the exposed conductors in the indentations 63 respectively serve as the outer electrodes 64. In such a multilayer electronic component 61, when a conductor is applied to the inner peripheral surface of each of the through holes 66, the conductor inevitably adheres to the periphery of the opening of each of the through holes 66. Consequently, exposed ends 64a of each of the external electrodes 64 are formed around the peripheries of both ends 63a of each indentation 63 on both major surfaces of the substrate 62.
FIG. 9 shows the multilayer electronic component disclosed in Japanese Patent Laid-Open No. 6-96992 (Laid-Open Date: Apr. 8, 1994). As shown in FIG. 9, a mother laminate 74 formed by stacking a plurality of insulating sheets with conductor films 83 and 84 interposed therein comprises via holes 79 respectively filled with conductors 78 and placed along grooves 80 for cutting the mother laminate 74 into respective multilayer electronic components. The conductors 78 respectively serve as external electrodes 72 of each of the multilayer electronic components obtained by cutting the mother laminate 74 along the grooves 80. In FIG. 9, reference numerals 81 and 82 denote slits which are respectively provided, along the grooves 80, at the bottoms of the grooves 80 of the mother laminate 74.
However, in the multilayer electronic component 51 shown in FIG. 7, since the external electrodes 53 are formed by applying a conductor, in some cases, the shapes of the ends 53a of the respective external electrodes 53 provided on both major surfaces 52c of the substrate 52 are not constant, and the dimensions thereof are greater than desired predetermined dimensions. When another electronic component is mounted on the substrate 52, therefore, the area where such electronic component can be mounted is limited, and it is also difficult to decrease the arrangement pitch (spacing) of the external electrodes 53. Further, since metallic paste must be applied to each of the side surfaces 52a and 52b of the substrate 52 for forming the external electrodes 53, much time is required for that work.
In the multilayer electronic component 61 shown in FIG. 8, as in the multilayer electronic component 51, in some cases, the shapes of the ends 64a of the respective external electrodes 64 provided on both major surfaces 64c of the substrate 62 are not constant, and the dimensions thereof are greater than desired predetermined dimensions. When another electronic component is mounted on the substrate 62, the area where such an electronic component can be mounted is restricted, and it is also difficult to decrease the arrangement pitch of the external electrodes 64. Although the through holes are formed by using a drill, moreover, it is also difficult to decrease the diameter thereof to less than a predetermined value, for example, 0.3 mm, thereby imposing a further restriction on the arrangement pitch of the external electrodes 64.
The characteristics of both multilayer electronic components 51 and 61 must be measured at least before shipment to the customer. However, in principle, such characteristics cannot be measured unless the multilayer electronic components are formed into chips which are functionally independent of each other. Namely, the characteristics of the multilayer electronic component 51 cannot be measured unless the external electrodes 53 are formed by applying metallic paste to the substrate 52. On the other hand, the characteristics of the multilayer electronic component 61 cannot be measured unless the external electrodes 64 are formed by cutting the parent laminate 65 to cut the through holes 66.
The multilayer electronic component shown in FIG. 9 is improved in the above respects. However, this electronic component also has a practical problem to be solved, namely that since the opposite inner walls of each of the grooves 80 are parallel with each other, it is necessary to either prepare a special measurement jig or to use a processing method which provides a sufficient groove width, in order to measure the characteristics of the respective multilayer electronic components while they are still in the form of the parent substrate, without the measurement jig producing short circuits.